Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
345 PM EDT Tue May 19 2026

Valid 12Z Fri May 22 2026 - 12Z Tue May 26 2026


...Multiple days of heavy rainfall expected for the south-central
U.S. through early next week...

...Overview...

Southern stream energy is forecast to move across the Southwest
Friday and slowly across the southern Plains this weekend and early
next week, bringing multiple rounds of showers and thunderstorms to
the region, potentially leading to flooding concerns. Meanwhile a
northern stream upper trough crossing the northern Plains and Upper
Midwest will push a frontal system through those regions into the
East, producing ample rain chances there as well. Then by early
next week, a stronger trough is forecast to arrive in the
Northwest, yielding cooler temperatures and precipitation.


...Guidance/Predictability Assessment...

Model guidance shows reasonable agreement through the weekend with
the primary features of note, including the north-central and
southwest to south-central upper troughs mentioned above. Typical
smaller scale differences could cause sensible weather differences
like placement of QPF, but these will likely remain uncertain into
the short range. The primary larger scale model variations are with
the trough moving toward and into the Northwest early next week.
The EC/CMC/AIFS and even the AIGFS and AIGEFS generally show a
slower track of the trough and potential embedded upper low
compared to the fast GFS runs. Continue to favor the larger
consensus rather than the progressive GFS. Note that the 12Z ECMWF
and CMC came in with around the same timing for the upper
trough/low Monday-Tuesday, but centered slightly north of their 00Z
runs, which may affect the southern extent of cooler temperatures
and rain.

Thus the early medium range forecast period used a multi-model
blend favoring the ECMWF and GFS for mass fields. As the period
progressed, lessened the proportion of the GFS and increased the EC
ensemble mean and AIFS.


...Weather/Hazards Highlights...

Multiple days of heavy rainfall are likely across the south-
central U.S. as upper-level energy provides lift atop a warm and
unstable airmass. Widespread thunderstorms and mesoscale convective
systems are possible and will likely peak this weekend across
eastern Texas into the Lower Mississippi Valley. Farther north and
east, moisture will be drawn ahead of the north-central U.S. trough
and spread across much of the Plains and Mississippi Valley to the
East Coast on Friday, with potential heavier amounts in the Mid-
South to Ohio Valley and Pennsylvania where a frontal system could
focus rain. Instability is lesser farther north, but moisture
anomalies are still above average. The Midwest should gradually dry
over the weekend, but rain chances are likely to persist across
the Ohio Valley and East into early next week. Due to these
features, the Day 4/Friday ERO features a Marginal Risk from the
Gulf Coast through the Mid-South and parts of the Ohio Valley into
Pennsylvania, with another Marginal centered over Oklahoma where an
MCS is likely and SPC also shows a severe threat. Then Day
5/Saturday, a Slight Risk is in place for southeast Texas into
Louisiana given the increasing rainfall totals likely by then. A
Marginal Risk surrounds the Slight while there is also another
Marginal Risk in the northern Mid-Atlantic and parts of the
Northeast, where recent models favor heavier rain, but this
Marginal looks especially prone to shifting around given the
amounts of model spread.

Troughing moving into the Northwest early next week will allow for
increased precipitation reaching the Pacific Northwest Sunday and
spreading east on Monday. Snow is possible at the highest
elevations of the Cascades to Rockies. The Four Corners states can
also expect increasing rain and thunderstorm chances by Monday.

In terms of temperatures, a cold air damming type event will
likely become established east of the Appalachians with overcast
skies and periods of mainly light rain at times to close out the
week, yielding cooler than average highs in the Mid-Atlantic and
southern parts of the Northeast into the weekend. Meanwhile,
relatively cool conditions across the central/northern Plains are
expected to gradually warm to above average through the forecast
period. The West should see warmer than average temperatures
through the weekend, but should cool west to east into Monday-
Tuesday underneath the trough.


Tate


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key
Messages are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw